Spec 17-19 Honda Civic Si Steel Flywheel
The SPEC SH99S-3 is a one-piece steel flywheel for the tenth-generation Honda Civic Si with the 1.5L turbo and six-speed manual. Owners usually come looking for it for one of two reasons: the factory flywheel has started to rattle, chatter or vibrate at idle and on takeoff, or a clutch upgrade is going in and they want a flywheel that will stand up to a tuned engine. This listing covers the 2017-2019 Civic Si.
The flywheel bolts to the crankshaft and gives the clutch disc its rear friction face. It also carries the ring gear the starter turns and stores rotating energy so the engine idles and pulls away smoothly. The Civic Si's L15B7 turbo four makes its torque low in the rev range, so the clutch and flywheel see a lot of load early, and a tune adds more.
SPEC builds the SH99S-3 from steel and lists it for the Civic Si and Accord four-cylinder with the note that it accommodates the OE pressure plate bolt pattern. That is the key difference from its siblings: SPEC's SH99S-SA (17 lb) is made only for SPEC's own proprietary clutch system, and the plain SH99S is a different flywheel for the Civic Type R. The SH99S-3 is the version for an owner who wants a steel flywheel under a clutch that keeps the factory pressure plate mounting. SPEC lists its weight at 26 lb, so this is a durability part, not a featherweight; it will not make the engine rev noticeably quicker.
A worn dual-mass flywheel often shows up as idle rattle and takeoff shudder rather than slip. Our dual-mass flywheel failure guide walks through the free-play and noise checks. If the car slips at full boost instead, the disc is usually the problem; a load test in fourth gear as described in our transmission slipping diagnosis guide separates the two. Grinding into gear points to clutch release or synchros, not the flywheel.
Our listing is for the 2017-2019 Honda Civic Si 1.5L turbo six-speed. SPEC's own application text is broader, listing the Civic Si and the Accord four-cylinder from 2017 through 2024, both for use with an OE pressure plate pattern. It does not fit the 2.0L Civic Type R, which takes a different SPEC flywheel. Clutch kits that ship with their own flywheel, such as the ACT HC10-HDSS and its matching ACT 601190 Streetlite flywheel, are designed around that flywheel and should not be mixed with this one. If you are unsure which pressure plate you are running, send us the year, VIN and clutch part number and we will confirm. More options are in our hard parts collection.
| Brand | SPEC |
| Part number | SH99S-3 |
| Fits | Spec 17-19 Honda Civic Si Steel Flywheel |
| Vehicle fitment | Honda Civic Si Steel (2017-2019) |
| Type | Flywheels |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
Yes, that is the application on this listing. SPEC also lists it for later Civic Si and the Accord four-cylinder through 2024 when used with an OE pressure plate pattern. Send your VIN if your car is outside 2017-2019.
No. The 2.0L Type R uses a different SPEC flywheel (SH99S). The SH99S-3 is for the 1.5L turbo Civic Si and Accord applications SPEC lists.
It is made for a clutch that uses the OE pressure plate bolt pattern. Kits that include their own flywheel, or SPEC's proprietary system that uses the SH99S-SA, are not a match. Send us your clutch part number if you are unsure.
SPEC lists the SH99S-3 at 26 lb. It is built for strength and durability rather than quicker revs.
Replace the clutch disc, pressure plate, release bearing and pilot bearing at the same time, use new flywheel bolts, and refill with Honda manual transmission fluid.
